diff --git a/documentation/development.md b/documentation/development.md
index 869427a70..652b6564a 100644
--- a/documentation/development.md
+++ b/documentation/development.md
@@ -305,3 +305,25 @@ final class YourEntityImageBuilder implements OGImageBuilderInterface {
 
 }
 ```
+
+
+## First paragraph grey alter
+
+There are some paragraphs that we want to "blend" with the hero-block if they are directly after the hero such as
+searches. Good example of this kind of search is `unit_search`. The grey background should continue from hero to the
+paragraph seamlessly and for paragraphs that are usable on all instances this is done in the `helfi_platform_config`.
+These paragraphs can be found listed in the `$paragraphs_with_grey_bg` variable in `HeroBlock.php`.
+
+There can be paragraphs that we want to function this way, but they are instance specific. For them to be able to
+function the same way you need to use the `first_paragraph_grey_alter` on that instance that uses the paragraph.
+
+Here is an example on how this is done in front page instance (helfi_etusivu custom module, helfi_etusivu.module file):
+
+```php
+/**
+* Implements hook_first_paragraph_grey_alter().
+*/
+function helfi_etusivu_first_paragraph_grey_alter(array &$paragraphs): void {
+  $paragraphs[] = 'news_archive';
+}
+```
diff --git a/helfi_platform_config.api.php b/helfi_platform_config.api.php
new file mode 100644
index 000000000..0eb428406
--- /dev/null
+++ b/helfi_platform_config.api.php
@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * @file
+ * HELfi platform config hooks.
+ */
+
+declare(strict_types=1);
+
+/**
+ * @file
+ * Hooks provided by the HELfi platform config module.
+ */
+
+/**
+ * Modify the list of paragraphs of first-paragraph-grey.
+ *
+ * The paragraphs on the list will get the special class
+ * has-first-paragraph-gray.
+ *
+ * @param array $paragraphs
+ *   Array of paragraph machine names.
+ */
+function hook_first_paragraph_grey_alter(array &$paragraphs) {
+}
diff --git a/modules/helfi_eu_cookie_compliance/helfi_eu_cookie_compliance.install b/modules/helfi_eu_cookie_compliance/helfi_eu_cookie_compliance.install
index 26792101d..dbf36bd0d 100644
--- a/modules/helfi_eu_cookie_compliance/helfi_eu_cookie_compliance.install
+++ b/modules/helfi_eu_cookie_compliance/helfi_eu_cookie_compliance.install
@@ -91,4 +91,4 @@ function helfi_eu_cookie_compliance_update_9011(): void {
 function helfi_eu_cookie_compliance_update_9012(): void {
   \Drupal::service('helfi_platform_config.config_update_helper')
     ->update('helfi_eu_cookie_compliance');
-}
\ No newline at end of file
+}
diff --git a/src/Plugin/Block/ContentBlockBase.php b/src/Plugin/Block/ContentBlockBase.php
index b55fbba67..64876af2d 100644
--- a/src/Plugin/Block/ContentBlockBase.php
+++ b/src/Plugin/Block/ContentBlockBase.php
@@ -7,6 +7,7 @@
 use Drupal\Core\Block\BlockBase;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\helfi_platform_config\EntityVersionMatcher;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -30,6 +31,13 @@ class ContentBlockBase extends BlockBase implements ContainerFactoryPluginInterf
    */
   protected EntityVersionMatcher $entityVersionMatcher;
 
+  /**
+   * The module handler.
+   *
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
+   */
+  protected ModuleHandlerInterface $moduleHandler;
+
   /**
    * {@inheritdoc}
    */
@@ -39,10 +47,12 @@ public function __construct(
     $plugin_definition,
     EntityTypeManagerInterface $entity_type_manager,
     EntityVersionMatcher $entity_version_matcher,
+    ModuleHandlerInterface $module_handler,
   ) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
     $this->entityTypeManager = $entity_type_manager;
     $this->entityVersionMatcher = $entity_version_matcher;
+    $this->moduleHandler = $module_handler;
   }
 
   /**
@@ -60,6 +70,7 @@ public static function create(
       $plugin_definition,
       $container->get('entity_type.manager'),
       $container->get('helfi_platform_config.entity_version_matcher'),
+      $container->get('module_handler'),
     );
   }
 
diff --git a/src/Plugin/Block/HeroBlock.php b/src/Plugin/Block/HeroBlock.php
index 6ebd5270b..22f754308 100644
--- a/src/Plugin/Block/HeroBlock.php
+++ b/src/Plugin/Block/HeroBlock.php
@@ -56,6 +56,9 @@ public function build() : array {
           'service_list_search',
         ];
 
+        // Let modules alter the array of paragraphs with grey background.
+        $this->moduleHandler->alter('first_paragraph_grey', $paragraphs_with_grey_bg);
+
         if (
           $paragraph instanceof ParagraphInterface &&
           in_array($paragraph->getType(), $paragraphs_with_grey_bg)